Tobacco smoke exposure results in a significantly increased life-long risk for numerous inflammatory lung diseases. Fetal and neonatal exposure to tobacco is a major risk factor for chronic lung disease of prematurity, which affects an extremely vulnerable population, with an estimated burden of more than $2.5 B/yr. in the US. Epidemiological studies strongly support a causal association between smoking history and COPD, the third leading cause of death in the US and lung cancer, the leading cause of cancer death for both men and women. Animal models and in vitro systems have been used, in combination with studies of human disease samples, to identify disease-associated pathways. Unfortunately, while the health risks of tobacco smoke exposure are widely-appreciated, there are no existing in vitro tests to ascertain risks associated with exposure burden or different type of tobacco products. We hypothesize that specific, reliable changes in gene expression can serve as biomarkers of tobacco smoke exposures that are accurate and predictive of human disease risk. The goal of this Project is to develop cell-based assays for specific disease-relevant gene expression signatures of cigarette smoke exposure. We propose three Specific Aims: The first Aim will survey genome-wide responses to tobacco smoke in vitro and ultimately result in a set of transcriptional biomarker sets which are accurate and predictive of human disease. The second Aim will define specific, physiological responses to inhaled smoke from a variety of tobacco types and doses within the lung, using a validated mouse model of smoke-induced lung disease. This Aim will also identify distinct responses in adults and more vulnerable juveniles and neonates. The third Aim will help to refine the set of biomarkers to focus upon whose dysregulation are observed in human lungs upon tobacco smoke exposure and/or in resulting disease states, and assess the predictive potential of those specific biomarkers. This project is highly responsive to the goals of the Program and will support the FDA mission to regulate tobacco products by developing multiple, disease-relevant, regulatory-appropriate assays that could be used by the FDA to quantitatively and qualitatively measure the adverse impact of tobacco smoke exposure.